Reversible stacking and unstacking mechanisms



Sept. 27, 1960 J. c. H. GEISOW REVERSIBLE STACKING AND UNSTACKING MECHANISMS 3 Sheets-Sheet 1 Filed Nov. 1, 1957 JOHN CHRISTOPHER HOWARD GEISOW Inventor Attorneys Sept. 27, 1960 J. c. H. GEISOW 2,954,133

REVERSIBLE STACKING AND UNSTACKING MECHANISMS Filed Nov. 1. 195 3 Sheets-Sheet 2 JOHN CHRISTOPHER HOWARD GEISOW Inventor Attorneys Sept. 27, 1960 J. c. H. GEISOW REVERSIBLE STACKING AND UNSTACKING MECHANISMS 3 Sheets-Sheet 3 Filed Nov. 1, 1957 JOHN CHRISTOPHER HOWARD GEISOW Inventor $10 K Va 37 Attorneys REVERSIBLE STACKING AND UNSTACKING MECHANISMS John Christopher Howard Geisow, Abingdon, England,

assignor to The United Kingdom Atomic Energy Authority, London, England Filed Nov. 1, 1957, Ser. No. 693,878 g Claims priority, application Great Britain Nov. 3, 1956 s Claims. c1. 214-6 This invention relates to reversible stacking and un-.

stacking mechanisms, and relates particularly to mechanisms for stacking and unstacking a series of substantially fi-at bodies having substantially the same dimensions.

According to the present invention a reversible stackmg and unstacking mechanisms for a series of substan tially flat bodies having substantially the same dimen-- sions comprises a pair of hollow cylindrical cams, each of the cams being a mirror image of the other and each having a profile comprising a substantially helical portion and a portion substantially parallel to the axis of the cylinder, means for causing the cams to contrarotate in phase on parallel axes in either direction according as the mechanism is required to stack or unstack, first guide means extending within the cams and adapted to locate the'bodies with respect to the cams, and second guide means substantially normal to the first guide means and also adapted tolocate said bodies with respect to said cams, whereby bodies are transferred from the first guide means to the second guide meansand vice versa according to the direction of rotation of the cams, the substantially helical portions of the profiles controlling movement within the first guide means and the substantially parallel portions thereof coni arrows marked S the arms stack. In Fig. 4 both guide systems are omitted for clarity; in Fig. 3 whichis a trolling movement-within the second guide means.

When stacking, means are required for [feeding the bodies along the first guide means and, when unstacking, along the second guide means. -The means for feeding the bodies along the first guide means may comprise a second reversible stacking and unstacking mechanism according to the invention driven in synchronism with the first-mentioned mechanisms but in the opposite direction. The means for feeding the bodies along the second means may be gravity.

In one embodiment of the invention flat trays containing radioactive samples or radiation absorbers are stacked in two vertical towers, each tower having a mechanism according to the invention installed at the base thereof and the two mechanisms being driven in synchronism but in opposite directions. Control means are provided whereby the trays can be passed discontinuously from the first tower to the second tower through a lead castle containing a Geiger-Miiller counter, each tray remaining within the castle long enough for a count to be made. By causing the control means to reverse the direction of drive, the trays can then be passed back continuously through the castle and restacked in the first tower.

For a clearer understanding of the invention, attention is directed to the accompanying drawings which illustrate, by way of example, an embodiment of the invention. In these drawings:

Fig. 1 is a perspective view of an embodiment of the invention with the second guide means removed to expose the mechanism.

Fig. 2 is a perspective view of an embodiment of the invention.

.Figs. 3 and 4 are diagrams illustrating the stacking and un-stacking action of the cams. Fig. 3 is a section taken on the line IIIIII of Fig. 1 looking in the direction of the arrows. Fig. 4 is a plan view of the arrangement of Fig. 3 with the phase of the cams slightlyv altered and the guide means omitted.

Fig. 5 is a modification of the embodiment of Fig. 2

constituting a radioactive sample changer or radiation absorber changer.

Fig.6 is a section along the line VI-VI of Fig. 5 looking in .the direction of the arrows, with the positions of two of the trays slightly altered.

,In Fig. l, 1 and 2 are hollow cylindrical cams arranged to rotate on parallel axes when driven by a shaft 3, through a gear train 4. The profile of each cam consists of a helical portion 5, a portion 6 normal to the axis of the cylinder and a portion 7 parallel to the axis of the cylinder. each other and rotate in phase relative to plane through their axes. A guide system to locate bodies with respect to the cams consist of a deck 8-para-llel to the plane of the cylinder axes, and side rails 9. The nails 9 extend within the hollow cams 1 and 2 and the deck 8 has slots 10 through which pass the walls'of the cams.

In Fig. 2a flat bodyll is shown resting on the deck 18, which is horizontal, between the rails 9, which are spaced apart by the width a of the bodies which the mechanism is designed to handle. A second guide system above thecams 1 and 2 consists of side walls 14,

a back stop 15 and front stops 16. The walls 14 are" Y spaced apart by the width a of the bodies and stops 15 and 16 by the length b thereof, so that when'stacked on top of each other above the earns the bodies are accurately located with respect thereto. The portions 6. of the cam. profiles extend slightly beyond the inner "faces of the-stops '16 and the portions 7 of the cam profiles extend at least as far back as the stop 15.

Figs. 3 and 4 illustrate the action of the cams. rotating in the direction of the arrows marked U the arms unstack and eject; when rotating in the direction of the section of the line IIIIII of Fig. 1 looking in thedirection of the arrows, only the deck 8 and rails 9 of the stacked one above the other above the cams, located,

7 by walls and stops 15 and 16. The lowest body is resting on the outer curved surfaces 17 of the cam cylinders and is therefore located at a level above the deck' 8 corresponding to a linedrawn tangentially to the sur-' As thecams turn in the unstack di-" faces of the cams. rection, the portions 7 of the cam profiles come into contact with the underside of the lowest body and, as the cams continue to turn, the body is lowered to the deck (Fig. 3). The helical portions 5 of the cam profiles now exert pressure on the corners of the body and eject it as shown in Fig. 4 under the stops 16 (Fig. 2). The height of the outer curved surface 17 of the cam above the deck 8 has to be made slightly greater than the thickness of the bodies, for reasons connected with the stacking action. The faces of the helical portions 5 of the cam profiles are therefore chamfered at 25 to avoid fouling the body above that being ejected. When the profile portions 6 are in contact with the rear edge of the body, the latter is then clear of the inner face of the stops 16 and so, as the cams continue turning, the next body, which has been resting partly on the surface 17 and partly on the top surface of the body being ejected, is likewise lowered from the stack and ejected, pushing the first body in front of it along the deck 8.-

- l atnted Sept. 27,- 1960 Ihe cams are mirror images of,

When

One 'body is thus unstacked and ejected for each complete revolution of the cams.

When stacking, the cams are rotated in the opposite direction. The bodies are moved along the deck 8 towards'the'cams 'by anexternal force, such as the *pressure-of succeeding bodies pushing from behind. Each body in turn passes under the stops 16 and comes up against the stop 15. The portions 7 of the-camprofiles now lift it into the stack under any other bodies already stacked therein, the lowest of which was resting on the surfaces 17. The next body now moves under stops 16 below' the bodies already stacked and is likewise lifted. One body is thus stacked for each complete revolution of the cams. The corners 2'6 where portions 6 and 7 of 'the cam profiles meet are rounded and chamfered so that the leading edgeof a following body slips back off the cams and is not lifted to jam againstthe undersides of the stops .16.

In'the modification of Fig. two of the mechanisms are used to pass a series of trays 18, carrying radioactive samples or radiation absorbers of different thicknesses back and forth through a lead castle 20 containing a Geiger-Muller counter. The Perspex trays 18-have holes 19 cut in them to carry the samples or absorbers. One stacking and unstacking mechanism 21 is located on one side of the lead castle 20; there is'a similar mechanism (not shown) on the other side and the two mechanisms are driven'in opposite directions.

The distance between the portions6 of thetwo pairs of .cams is made an integral number of times thelength of the trays (three times in this example), and the pairs of cams are so phased that the ejecting action of one pair of cams feeds the .fourth tray in front to the-other pair of (stacking) cams at the correct time.

Since the portions 6 of the pairs of cams have to be located slightly beyond the inner surfaces of their respective stops 16a (so that an ejected body .is pushed clear of the one above) and the distance between the pairs of cams is fixed at an integral number of times thetlength of the trays, it follows that, when stacking, the rear edge of each tray .is not pushed clear ofthe inner face of the stop 16a by the following tray. The overlap is equal to the distance between the inner surface of the stop and the portions 6 of the cams. To prevent the tray being stacked jamming against the underside of the stop, the latter is charnfered as shown at 27 in Fig. 6 so that the tray slides back into the guide system as it is raised.

To provide a second bearing for the cams (which have to carry the weight of all the trays in the stack) the side rails 9 are expanded where they extend within the cams to provide curved surfaces 24 on which bear the inside curved surfaces of the cams.

The pairs of cams can be controlled to rotate in either direction; discontinuously in one direction, so that each tray remains within the castle long enough for a count to be made; and continuously in the other direction, so

4. that the trays are fed back rapidly through the castle and stacked ready for a further counting run. A feeler arm at the base of each stack (not shown) may be arranged to inform a control mechanism when the stack is empty.

I claim:

1. Apparatus adapted to stack and unstack bodies arranged in series and having a flat bottom portion and at least one side wall, comprising at least one pair of hollow cylindrical .cams mounted for rotation and disposed in parallel in a first plane, the upper outside surfaces of said cams being disposed tangential to a second plane parallel to and spaced. apart fromsaid first plane, said first and second planes being spaced apart at a distance greater than-the height of said bodies, first guide means mounted in said first plane adjacent said cams and adapted to engage said bottom portion, second guide means mounted normal to said second plane adjacent said cams and adapted to engage said side wall, and means disposed in said camsfor moving said bodies between said first and secondplanes, whereby with relative rotation of said cams said last-named means successively moves each said body out of engagement with one said guide means and into engagement with the other said guide means.

2. Apparatus according to claim 1 wherein said cams have substantially equal external diameters and said lastnamed means comprises oppositely disposed openings in said cams, each said opening having an edge parallel to the of said 'cam, an edge substantially helical, and an edge normal to said axis, whereby with counter rotation o'fsaid cams engagement of said parallel edge with said bot-tom portion and engagement of said helical edge with said side wall moves each said body successively out of engagement with one said guide means and into engagement with the other said guide means.

3. Apparatus according to claim 2 wherein said second guide means comprises a tubular member superimposed upon said cams with the longitudinal axis thereof extending upwardly normal -to said second plane and centrally between the axes of said cams, said tubular member being adapted internally to engage said side wall.

4. Apparatus according to claim 2 wherein said cams are spaced apart and said first guide means comprises a flat surface extending between said cams andcoplanar with said first plane.

5'. Apparatus according to claim 4 wherein said first guide means further comprises side rails extending within said hollow cams and adapted to engage said side wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,365,741 Speer Ian. 18, 192.1 1,703,637 Reifsnyder Feb. 26, 1929 1,907,713 Benson May 9, 1933 2,595,013 Smith Apr. 29, 1952 

